Tadalafil use fails to improve lung function, quality of life in patients with severe asthma: Study

Asthma is a chronic respiratory disease that affects over 300 million individuals worldwide. This condition is caused by the reaction of the immune system to allergenic particles and substances, leading to increased inflammation, mucus secretion, hyperresponsiveness of the respiratory tract mucosa, smooth muscle contraction, and difficulty breathing during asthma attacks. The primary objective of asthma treatment is to reduce airway inflammation and reverse bronchoconstriction.

Phosphodiesterase inhibitors increase cyclic guanosine monophosphate and cyclic adenosine monophosphate levels, which have been associated with several anti-inflammatory effects that can help alleviate asthma symptoms. Tadalafil, a selective PDE5 inhibitor, prevents the degradation of cGMP and raises its levels. However, the human studies on the effects of specific phosphodiesterase inhibitors (PDE) on pulmonary function are limited leading to the need for experimental studies.

To fill this knowledge gap, Seyed Hamid Borsi, Air Pollution and Respiratory Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, and colleagues aimed to assess the impact of Tadalafil, a selective phosphodiesterase inhibitor, on asthma severity and lung function in patients with severe asthma.

For this purpose, they conducted a randomized, double-blind clinical trial in 2021 at Imam Khomeini Hospital in Ahvaz, Iran. Forty-four patients with severe asthma were enrolled; they were equally divided into a Tadalafil group and a placebo group. The Tadalafil group received 20 mg/day of Tadalafil, while the placebo group received a placebo at the same dose.

The patients' asthma quality of life questionnaire, spirometry tests, quality of life, and 6-minute walk distance were measured at the study's beginning and one month later.

Key findings of the study:

• There was no statistically significant difference between the Tadalafil group and the placebo group in terms of pulmonary parameters.
• The scores for patients' quality of life and the 6-minute walk test at the end of the study did not show any statistically significant improvement compared to the placebo group.

"The results suggest that administration of a daily dose of Tadalafil (20 mg) for one month in patients with severe asthma had no impact on subclinical or clinical outcomes, such as improvements in 6-minute walk distance, lung volume (FEV1, FVC, FEV1/FVC, FEF25-75), and overall quality of life," the researchers wrote.

"There is a need for further investigation with longer follow-up periods and larger sample sizes to evaluate the clinical and laboratory effects of other phosphodiesterase," they concluded.

The limitations of the study include a small sample size, the inclusion of only severe asthma patients, and short follow-up duration. PDEs may potentially affect mild or moderate asthma cases.

Reference:

Borsi SH, Fakhr Mousavi SAAFM, Dargahi Mal-Amir M, Tavakol H, Raji H. Evaluation of the effectiveness of Tadalafil on improving pulmonary function and asthma severity in severe asthmatic patients: a randomized controlled trial study. Monaldi Arch Chest Dis. 2024 Jan 11. doi: 10.4081/monaldi.2024.2685. Epub ahead of print. PMID: 38213275.